Build a 6.5-06 and you can use your old 270 brass to neck down and cut to length. Those 130 gr. And 140gr. 6.5mm bullets are hard to beat. It has basically the same ballistics as the 6.5x284- brass is easier to get and cheaper- neck up 25-06 brass.
The 280AI would be a good one too, have better bullet selection, but it does not feed through the action as good as the 6.5-06 case, that 40 degree shoulder seems to catch sometimes. Recoil will be more too.

I'm in the process right now of taking my 721 30/06 and turning her into a 280AI. I deliberated on this for a while and just couldn't get away from all those slippery 7mm pills out there and knowing it'll have enough punch to take down just about anything i will find myself hunting.